The present invention relates generally to a fixture for holding a workpiece, and more particularly, to a fixture which firmly holds the workpiece without deforming or displacing the workpiece.
Fixtures are commonly used to hold workpieces in desired locations and orientations when performing manufacturing operations. Such fixtures generally include a support having one or more reference points which engage points on the workpiece for locating and orienting the workpiece. These fixtures also include one or more clamps for clamping the workpiece against the reference points to hold the workpiece in the predetermined position. Any workpiece movement can adversely affect the manufacturing operation. For instance, if the workpiece moves during a grinding operation, surfaces on the workpiece may be ground to an improper shape.
Even if the clamps firmly hold the workpiece against the reference points, the workpiece may still deform (i.e., flex) between the clamps and thereby affect the manufacturing operation. To prevent the workpiece from deforming, one or more braces are sometimes mounted on the support between the clamps. Frequently, these braces are retractable so they do not interfere with the workpiece when it is located on the reference points. The braces are retracted when the workpiece is positioned on the reference points and extended into position after the workpiece is clamped in place. However, due to variations in dimensions from workpiece to workpiece, the braces may not precisely meet the workpiece when extended. There may be gaps between the braces and the workpiece which permit the workpiece to deform during the manufacturing operation. Further, the brace may interfere with the workpiece as it is extended, causing the workpiece to deform. Therefore, unless the brace precisely meets the workpiece, the workpiece can deform and adversely affect the manufacturing operation.